SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dc3937ae30be84407e6e10af49e60f4e1b65e5a26cf1542d7ff5230bd2431d78' 
  AND token = 'PxcKhl6/rUsE4ZqB0JvxFshleLiCwgvwBBl7FoI6guQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}